The night was dark and the weather was treacherous on the night which Macbeth held his banquet to celebrate himself becoming king, and to secretly celebrate the murder of Banquo...
When one of the murderers Macbeth had hired told him that Banquo is dead but Fleance had escaped Macbeth became very anxious. The plan had failed.
People soon realized that the mood of the party matched the weather. Weird things began to happen...when a guest asked Macbeth to take his seat he claimed he couldn't because someone was in it. But the guests didn't see anyone..
Seeing Banquo in his seat angered Macbeth greatly and so he cried at the empty seat in front of everyone "Never shake thy gory locks at me!"
Lady Macbeth then swiftly rose and excused Macbeth's behavior as something he'd done since his childhood and explained that the fit would only last momentarily.
But Macbeth's behavior became more and more erratic and Lady Macbeth was forced to tell everyone to evacuate immediately without order! The King was not well! Question enraged him!